1. Field of the Invention
The present invention relates to thermal transfer printing. More particularly, the present invention relates to a thermal transfer printing method and apparatus requiring low rating.
2. Description of the Related Art
In general, in a thermal transfer printing method, each main line is printed in a unit of a block such that the thermal transfer printing method is suitable for use in a small-sized printing apparatus, such as a portable printer. However, in the thermal transfer printing method, printing data received from a personal computer (PC) must be converted into heat so that heat is transferred to a thermosensitive film and data is printed on a sheet of paper in a unit of a main line. Thus, in a conventional thermal transfer printing method, a considerably large amount of energy is consumed at a single instant. For example, when the number of dots per inch is 300 and a unit main line is comprised of four blocks, assuming that the number of dots included in each block is 720 and power consumption per dot is 0.26 watts, the maximum amount of power consumed during printing in each block is 187.2 watts and the maximum amount of power consumed during printing in each line is 748.8 watts. Accordingly, when a large amount of data is included in each line, a considerably large amount of power is consumed at a single instant such that the rating of a portable printer using a conventional thermal transfer printing method may be over 190 watts.
Consequently, a printing apparatus using the conventional thermal transfer printing method, which consumes a large amount of energy at a single instant, requires a DC power supply unit (or AC/DC power adaptor) having large rating. In this case, as the rating of the printing apparatus increases, the size of the DC power supply unit increases. Thus, a user using a portable printer applying the conventional thermal transfer printing method needs to carry a heavy and bulky DC power supply unit. Further, due to an increase in maximum power consumption caused by an increase in the amount of data, when the printing apparatus using the conventional thermal transfer printing method uses a common battery with another apparatus, such as a portable and personal printer, the battery capacity of the printing apparatus must be increased so that power required by another apparatus is supplied when the printing apparatus requires a large amount of energy at a single instant.